Drum for inclined axis concrete mixers



Oct. 21, 1952 c. l. LONGENECKER 2,614,819

DRUM FOR INCLINED AXIS CONCRETE MIXERS Filed June 7, 1950 I N V EN TOR. Charles 1: Longene c/rer,

ATTORNZ;

Patented Get. 21, 1952 UNITED STATES PATENT" OFF-ICE 14,819 DRUMFURQINGL'INEDAFEISCONCRETE MIXERS lam -,L9em auw wm W '1 i n a ha n, lt LH I W matte, Wis-a tc nnwhni s o su applicazmnlunem, 1950;, sun;i ilim1 53 31;;

L St at o 39%992 e a eDecem t 1?, 1942. a i

As is Well known to those;skilled in this art, the drums of mixi-n g apparatus' of this, character usually are of coniform shape; are mounted for power-driven rotation about their lo glt dir al axis, which is fixedlyihclined tq thethori'zorital at an angle on the order of 209'; are closed at their larger, 1owe1g end" while their smaller, higher end is: provided withamaterial-trahsfer opening, through which discharge is; prevented duri'hgthe mixing period. by an appropriatefread'ily. movable closure structure; and their; p'erimetfic Wall's carry a p lurality of internal helically arranged mixing blades. which function durihg rctation-v of the drum to agitate and co mrhingle' the, concretemaking materials, as .well asltjo move them toward one end or the otherof the"drum, dependihg upon the direction of rotation oil the latter,

Briefly, the aforementioned patent pjointed out that, prior thereto the usual practice of the art was to rotate the drum int l ghd ireb'tion during mixing that the helical blades would prop el' the materials away from the open end an cltoward the closed end of the drum andl to reverse the direction of rotation of the drum, and consequently the direction of longitudinal movement of he mi u eto fiect i char e '1 th e r. ro h o en nd of he. m t ur h r P in e ut ha e t in disadva age Qf hi standard procedure could be avoided and better and faster mixing and discharge attained,

hro gh unidir lc i a O eration o h r m ur n th. h m in d. he d sc ar periods, whereby perimetral portions ,ot the batch were always moved upwardly away frorl the closed end and, toward the; open. discharge end ofthe drumby the hellcallblades andthroughout he m i pe he pfe te t mate a s fca wded7 d wnwan lyi ow rd h q ed, ni in the open corev space defihed generally by the inward edges of said bladesl While extensive, experience with; mixers oqer-t a d: n. qq d nce w th the rinq l'es i c fl n aid tent m.lswfl z es bst j t w laim sup io i y f i mode q r: 1. a n discharge over the; prior practice; 1: 11mm fo md that t'l'ie aetipni i'n. such drums 111343? be ki-1 r heamproved? u h the b l 1 o oneltmqrl un kmentalfg a es di os d Within the core, space arid extending longitudinally thereof throi igholituat leasta major p rtion of thej ler gtlt oi the drum. Sll'h SuDIJIenie ntal blades ma" he, suppor ed by] the drum. shell 1 mm elical blaqes, carried thereby solas tn eemm; andth ey alreso set with o thefli'nelined axisoflthe, rum that u re the mi'd poi1 1t' in. thei'rfarc oi maw r r lhey ar sub tan a l hor q 'Il'iev rinci'palactioh' of si oh bladesifs to impart ater'ialin thecore ransyj erse of the pass 1 beyond, saidl midv erselyl i'nclir ied. they; also mar en llf hl f iews pe o ite y lleu e 5: in e directioiigof the arrows.

. ngjffpr the drum, the mechg th same, and the, devices for s. d/1 i c trol in the 111181 tom the drtmiv christim le Q 95 he i 'htibn, and are not essenth fiowei ft ey heya 813mm lent of those setouti the above:

e itjNo 2; 3 902.

ta ma e re e d ail. h a) cdhiform" shell I I, the s o e iit l mvifi a m hr ugh, whi h, he m iil to'. and discharged from gel: end of tlieshell isclosed '1 whl'sli- Qair' l sa k t 1e thd d'ru m may be. rotated 1 gri'sA- B which as willvbe i he; e entia nvent nal 4 V edges 'of the helical blades, and the inward longitudinal edge portion of the blade 22 is bent as at 21 to provide an angularly disposed lip 28 extending throughout the length of the blade, in the region of the drum axis.

1 In the drawing the blade 22 is shown as having reached the mid-point of its sectorof-upward travel (when the drum is rotating "counterclockwise as viewed in Fig. 3), and it isso angularly tending longitudinally of the drum throughout at least a major portion of its length. At the higher,

smaller end of the drum these blades terminate in sections l8 shaped and disposed to facilitate discharge of themixture through the transfer opening [2 when the closure structure associated therewith (but not here shown) is opened. The

rearward portions of the helical blades I? may be provided with flanges 19 extending angularly from the inward edgesZll of the blades, for assisting in the mixing, conveying and discharging functions of the latter; andthe inward surfaces 2i of these flanges, together with the inward edges 20 of the unflanged portions of the blades, in general define the above mentioned central core space of the drum'in which the forward fcascading of thematerials takes place.

Ordinarily each batch of materials treated in a drum of this character occupies at least 50%, and usually more, of the volumetric capacity of the drum, but of course it should never be completely filled as some free space is necessary in which the materials may tumble and cascade in order'to attain proper commingling thereof. As set forth in said prior Patent No. 2,303,902, when a drum containing a batch of concrete-making materials equivalent to say 60% of the volumetric capacity of the drum is rotated in the direction indicated by the arrows in'Figs. 2 and 3 of th'e'present drawing, the helical blades 17, acting more or less as a screw conveyer, continuously move perimetral portions of the said batch upwardly and to ward the right, as viewed in Fig. 1; and, assuming the closure structure to be in operative position relative to the opening 12, when such portions are discharged from the sections 18 ,of the blades they gravitationally cascade downwardly and forwardly (or toward the left) in the central core space. These movements of the materials result in the upper surface of the batch assuming a downward longitudinal slope from the rear end of the drum, somewhat as indicated by the line CD in Fig. 1; and because of the rotational effect of the drum on the materials, said upper surface also assumes a, transverse slope,v when viewed in cross section, approximately as indicated by the line EF in Fig. 3.

As above stated, I have ascertained from actual positioned in relation to the inclined axis of rotation of the drum'that at this time the body portion 23 is approximately horizontal, as will be clear from Fig. 1. It is at about this time that the blade emerges from the top of the batch, its

, breaking of the surface occurring first at its forward end adjacent the header l3 and, due to the longitudinal slope CD of the batch surface,

progressing rearwardly to the end supported by the bracket 25. In general its action is to lift trial that the mixingaction thus attained may be further improved by the use of one or 'more supplemental blades disposed in and extending throughout at least a majorrportion of the length of the central core space; and one such blade 22 is illustrated in the present .drawing. As will be readily understood therefrom, the elongated generally rectangular, but slightly rearwardlytapering, body portion 23 of this blade is fiat and extends from the header structure l3, to which it may be attached by an angle bracket 24, to adjacent the discharge section H! of one of the helical blades H, by which it may be supported through the medium of a bracket 25 The outer longitudinal edge 26 ofthis supplemental blade coincides generally with the outer limit of the central core space as defined by the flanges l9 and portions of the batch and spill them transversely of the drum, over the edge of the lip 28, although as the rotation continues and the blade assumes something of a rearward downward slant, it may impart some rearward movement toward the opening l2 to any material remaining upon it. The supplemental blade imposes little if any interference withthe normal cascading of the materials forwardly downthe slopeC--D, and its demonstrated effect is to appreciably improve the mixing action and reduce the mixing time.

What is claimed is:

1. In concrete mixing apparatus of the class described, the combination ofa drum having a longitudinal axis'inclined to the horizontal and about which the drum is rotatable, the lower end of said drumbeing closed and the higher end thereof having a material-transfer opening; helically arranged mixing and conveying blades secured to and extending inwardly from the perimetric wall of said drum and adapted through rotation of the latter about its said inclined axis to continuously move perimetral portions of a batch of material in the drum away from the closed end of the latter and upwardly toward said material-transferopening, the inward edge portions of said helical blades defining a central core space in the drum in which the elevated portions of the material may cascade downwardly from the higher end of thedrum toward the lower end thereof; and an elongated substantially flat supplemental mixing blade disposed in and extending longitudinally of said core space to one side of the drum axis for imparting movement to portions of the cascading material in a direction transverse to the drum axis, one end of such blade, adjoining and being secured to the closed end of the drum while its other end is supported adjacent said material-transfer opening, the outward longitudinal edge of said blade being disposed substantially along the outer limit of said core space as defined by said inward edge D01- tions of the helical. blades, and the inward longitudinal edge of the supplemental blade lying in the region of the drum axis.

2. In concrete mixing apparatus of the class described, the combination of a drum having a longitudinal axis inclined to the horizontal and about which the drum is rotatable, the lower end of said drum being closed and the higher end thereof having a material-transfer opening; hel ically arranged mixing and conveying blades secured to and extending inwardly from the perimetric wall of said drum and adapted through rotation of the latter about its said inclined axis to continuously move perimetral portions of a batch of material in the drum away from the closed end of the latter and upwardly toward said material-transfer opening, the inward edge portions of said helical blades defining a central core space in the drum in which the elevated portions of the material may cascade downwardly from the higher end of the drum toward the lower end thereof; and an elongated supplemental mixing blade disposed in and extending longitudinally of said core space to one side of said drum axis, said blade comprising a substantially rectangular flat body member one end of which adjoins and is socured to the closed end of the drum while the other end of said body member is disposed and supported adjacent said material-transfer opening, the outward longitudinal edge of said body member being substantially coincident with the outer limit of said core space as defined by said inward portions of the helical blades, and the inward longitudinal portion of said body member lying in the region of said drum axis and having an angularly disposed lip extending therealong.

3. In concrete mixing apparatus of the class described, the combination of a drum having a longitudinal axis inclined to the horizontal and about which the drum is rotatable, the lower end of said drum being closed and the higher end thereof having a material-transfer opening; helically arranged mixing and conveying blades secured to and extending inwardly from the perimetric wall of said drum and adapted through rotation of the latter about its said inclined axis to continuously move perimetral portions of a batch of material in the drum away from the closed end of the latter and upwardly toward said material-transfer opening, the inward edge portions of said helical blades defining a central core space in the drum in which the elevated portions of the material may cascade downwardly from the higher end of the drum toward the lower end thereof; and a substantially flat supplemental mixing blade disposed in said core space to one side of said drum axis and rotatable with the drum, said supplemental blade extending longitudinally of the core space throughout a, major portion of the length of the latter, and being so longitudinally angularly disposed with respect to said drum axis that at the mid-point in the sector of upward travel of such blade it will occupy a substantially horizontal position whereby subl stantially all of the movement imparted to the portions of the material acted upon by said blade will be in a direction transverse to the drum axis.

CHARLES I. LONGENECKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,370,954 Ebersold Mar. 8, 1921 2,490,215 Hilkemeier et al. Dec. 6, 1949 FOREIGN PATENTS Number Country Date 6,537 Great Britain Mar. 17, 1904 726,959 France June 10, 1932 

